Semiconductor package with plated connection

ABSTRACT

A semiconductor package and method for making a semiconductor package are disclosed. The semiconductor package has a top surface and a mounting surface and includes a die, a conducting connecting material, a plating material and an insulating material. The die has a processed surface facing towards the mounting surface of the semiconductor package. Exposed metal connections are at the processed surface of the die. The conducting connecting material is disposed on the exposed metal connections. The plating material is in contact with the conducting connecting material. The insulating material is formed around the conducting connecting material, and the plating material extends to the exterior of the insulating material.

FIELD OF THE INVENTION

The present invention relates generally to semiconductors. Morespecifically, a semiconductor package and a method for semiconductorpackaging are disclosed.

BACKGROUND OF THE INVENTION

Semiconductor packages protect and secure an integrated circuit (IC),also referred to as a die, contained within the package. A packaged ICdevice is mounted on a printed circuit board (PCB) to interact withother devices on the PCB and/or with other PCBs. To ensure the properfunctioning of the packaged IC device and proper interaction with otherdevices, semiconductor packages are designed to meet specifiedtemperature, electrical and physical characteristics. For example,packages are designed to meet certain heat dissipation requirements,input/output impedance requirements and dimension requirements.

Flip chip packages are one type of semiconductor package. Instead ofusing bonding wires, flip chip packages use bonding balls toelectrically and mechanically connect the die to exterior connections ofthe flip chip package. It would be useful to develop advanced techniquesfor flip chip packaging of certain types of IC devices.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the invention are disclosed in the followingdetailed description and the accompanying drawings.

FIG. 1A illustrates a top view of an embodiment of a lead frame.

FIG. 1B illustrates a cross sectional view from view I of the leadframe.

FIG. 2A illustrates a top view of an embodiment of a conductingconnecting material attached to the processed surface of a die.

FIG. 2B illustrates a cross sectional view from view II of an embodimentof a conducting connecting material attached to the processed surface ofa die.

FIG. 3A illustrates a side view of an embodiment of a lead frameattached to a die.

FIG. 3B illustrates a side view of an embodiment of a lead frameattached to a die.

FIG. 4A illustrates a top view of an embodiment of a connector attachedto a die.

FIG. 4B illustrates a cross sectional view from view XL of an embodimentof a connector attached to a die.

FIG. 4C illustrates a cross sectional view from view XLI of anembodiment of a connector attached to a die.

FIG. 5 illustrates a cross sectional view of an embodiment whereinsulating material is formed around a plating material, conductingconnecting material and die.

FIG. 6A illustrates a cross sectional view of an embodiment with theremovable substrate removed.

FIG. 6B illustrates a bottom view from view VI of an embodiment with theremovable substrate removed.

FIG. 7A illustrates a cross sectional view where one raised leadreplaces multiple raised leads for the source.

FIG. 7B illustrates a bottom view from view VII of an embodiment whereone raised lead replaces multiple raised leads for the source.

FIG. 8A illustrates a cross sectional view of an embodiment where theplate extends to the exterior of the molding.

FIG. 8B illustrates a bottom view from view VIII of an embodiment wherethe plate extends to the exterior of the molding.

FIG. 9A illustrates a side view of an embodiment where the raised leadsextend to more than one exterior surface of the molding.

FIG. 9B illustrates a bottom view from view IX of an embodiment wherethe raised leads extend to more than one exterior surface of themolding.

FIG. 10A illustrates a top view of an embodiment where the shape of theplate is different from that illustrated above.

FIG. 10B illustrates a cross sectional view from view X of an embodimentwhere the shape of the plate is different from that illustrated above.

DETAILED DESCRIPTION

The invention can be implemented in numerous ways, including as aprocess, an apparatus, a system, a composition of matter, a computerreadable medium such as a computer readable storage medium or a computernetwork wherein program instructions are sent over optical or electroniccommunication links. In this specification, these implementations, orany other form that the invention may take, may be referred to astechniques. In general, the order of the steps of disclosed processesmay be altered within the scope of the invention.

A detailed description of one or more embodiments of the invention isprovided below along with accompanying figures that illustrate theprinciples of the invention. The invention is described in connectionwith such embodiments, but the invention is not limited to anyembodiment. The scope of the invention is limited only by the claims andthe invention encompasses numerous alternatives, modifications andequivalents. Numerous specific details are set forth in the followingdescription in order to provide a thorough understanding of theinvention. These details are provided for the purpose of example and theinvention may be practiced according to the claims without some or allof these specific details. For the purpose of clarity, technicalmaterial that is known in the technical fields related to the inventionhas not been described in detail so that the invention is notunnecessarily obscured.

A process for packaging a semiconductor using a plate attached to onesurface of a die is disclosed. A lead frame, composed of a removablesubstrate and a plating material, is constructed. On the processedsurface of the die, exposed metal connections are formed duringmanufacture of the die. A conductive connecting material is attached ontop of the exposed metal connections. The lead frame and die areconnected such that the conductive connecting material lines up andconnects to the plating material of the lead frame. In some embodiments,a connector is attached to the unprocessed side of the die and theplating material using a conducting adhesive. Preferably, the connectoris a tape type interconnect. A molding material is injected around thedie, plating material and the connector. The removable substrate ispeeled away to expose the plating material. In some embodiments, thepeeled parts are cut into separate components.

FIG. 1A illustrates a top view of an embodiment of a lead frame. In thisexample, frame 100 includes a plating material 104 that is deposited ona removable substrate 102. As is described below, plating material 104forms a connection to the outside of a semiconductor package when theremovable substrate is peeled away. Removable substrate 102 is a flatpiece of metal or plastic or other material. Seven areas of platingmaterial 104, also referred to as raised leads, are shown plated onremovable substrate 102. Gold or other noble metals are used for raisedleads 104 and in the embodiment shown raised leads 104 are formed usingphotolithography. Removable substrate 102 is made of one or a couple ofalloys which can be peeled away after molding.

FIG. 1B illustrates a cross sectional view from view I of the leadframe. In this example, raised leads 104 are in the same plane.Removable substrate 102 provides a flat base that supports raised leads104 during the packaging process. While plated on removable substrate102, raised leads 104 remain in a fixed position with respect to eachother. Removable substrate 102 also provides a convenient handle formachines that perform steps in the packaging processes. For example,various machines can grasp removable substrate 102 to rotate, attachother materials to or transport the device. Removable substrate 102 isremoved in the packaging process and raised leads 104 are integratedinto the package to provide electrical connections for the packaged ICdevice.

In some embodiments, the forms and dimensions of the raised leads aredifferent from that illustrated. For example, the shapes of the raisedleads 104 may have rounded edges instead of straight edges by changingthe mask set used during the photolithography process. In someembodiments, the dimensions of raised leads 104 are modified to changethe electrical properties of the electrical connections that raisedleads 104 provide. For example, in some applications it may be useful toreduce the electrical resistance through raised leads 104. By changingthe dimensions (e.g., length, cross sectional area, etc.) the electricalresistance may be reduced.

FIG. 2A illustrates a top view of an embodiment of a conductingconnecting material attached to the processed surface of a die. In thisexample, the conducting connecting material is a gold ball. Die 210 hasa processed surface 206. Processed surface 206 is the side of die 210 onwhich semiconductor processes (e.g., photolithography, etching, etc.)have been applied. For example, one or more metal layers may be appliedto create routing paths and pads on processed surface 206. Gold balls203 are attached to processed surface 206 using ultrasonic or otherappropriate techniques and provide electrical connections for thepackaged IC device.

FIG. 2B illustrates a cross sectional view from view II of an embodimentof a conducting connecting material attached to the processed surface ofa die. In this example, there are three gold balls 203, three exposedmetal connections 212 and die 210. The three gold balls 203 are attachedto exposed metal connections 212, also referred to as input/output (IO)pads. Die 210 has a processed surface 206 and an unprocessed surface 208opposite. Processed surface 206 includes pads 212. In some embodiments,pads 212 are exposed through contact openings by etching through apassivation layer of dielectric material protecting the processedsurface 206. Gold balls 203 are formed on pads 212 and provideelectrical connections for the packaging of IC device.

FIG. 3A illustrates a side view of an embodiment of a lead frameattached to a die. In this example, die 300 is oriented such thatprocessed surface 314 is downward facing. Processed surface 314 includesthree pads 303. Pads 303 are connected to gold balls 307 which in turnare connected to the raised leads 311. The three raised leads are platedon removable substrate 315. Pads 303, gold balls 307 and raised leads311 provide electrical connections for the packaged IC device and theremovable substrate 315 is peeled away as described below.

FIG. 3B illustrates a side view of an embodiment of a lead frameattached to a die. In this example, not all of raised leads 311-313 areconnected to a gold ball. Raised lead 311 and 312 are connected to goldballs 307 and 308, respectively, but raised lead 313 is not connected toa gold ball. Pad 303 is connected to gold ball 307, which in turn isconnected to the raised lead 311 and pad 304 is connected to gold ball308, which in turn is connected to raised lead 312. Raised leads 311-313are plated on removable substrate 315.

Plating raised leads 311-313 on removable substrate 315 usingphotolithography allows for flexible placement of the raised leads. Forexample, if pads 303-304 are densely packed on processed surface 314,the mask set used during the photolithography process is retooled up toplate raised leads 311-312 closer to each other. Another example is ifthe placement of pads 303-304 is unusual or asymmetrical. The mask setused in the photolithography process is retooled up so that theplacement of the raised leads reflects any unusual or asymmetricalplacement of the pads.

FIG. 4A illustrates a top view of an embodiment of a connector attachedto a die. In this example, the connector is also referred to as a plate.In some embodiments, the connector is a tape type interconnect. Plate400 has two planes, one of which is illustrated in this figure. In thisview, the shape of plate 400 is a rectangle. When connected to die 402,plate 400 does not extend to the edges of die 402 at three of the fouredges. On the fourth edge, plate 400 extends beyond the edge.

FIG. 4B illustrates a cross sectional view from view XL of an embodimentof a connector attached to a die. In this example, plate 400 is attachedto die 402 using adhesive 404. Adhesive 404 may be an epoxy or solder.Using adhesive 404, plate 400 is attached to the unprocessed side of thedie 406. On the processed side of the die 408, pad 410 is connected togold ball 412. Gold ball 412 is connected to the raised lead 414, whichin turn is plated on removable substrate 416.

FIG. 4C illustrates a cross sectional view from view XLI of anembodiment of a connector attached to a die. In this example, plate 400is shaped such that there are two planes which are parallel to eachother. One plane of plate 400 is connected to unprocessed surface 406using adhesive 404. The other plane of plate 400 is connected to theraised lead 420 using adhesive 418. Adhesive 418 may be an epoxy orsolder. From this view, a raised lead is connected to either a gold ballor plate. Raised lead 414 is connected to gold ball 412 which in turn isconnected to pad 410. Pad 410 is on the processed side of the die 408.Raised lead 420 is attached to plate 400.

In this example plate 400 is made of copper. In some embodiments anothermetal is selected for its electrical properties. The metal may beselected for its thermal properties.

Connecting plate 400 to die 402 creates an electrical connection fromone side of the die to the opposite side of the die. This is useful whenpackaging a die which contains vertical elements. That is, elements havea higher or lower placement with respect to each other in the die whenthe processed surface (or conversely, the unprocessed surface) isdownward facing. In this example, one element (a drain) is located at ornear unprocessed surface 406 and other elements (the gate and source)are located at or near processed surface 408. Raised lead 414 istherefore electrically connected to a gate or source and raised lead 420is electrically connected to a drain. In some embodiments the verticalelements or orientation are different.

FIG. 5 illustrates a cross sectional view of an embodiment whereinsulating material is formed around a plating material, conductingconnecting material and die. In this example, insulating material 500 isapplied such that only insulating material 500 and removable substrate502 are exposed at the exterior. Insulating material 500 is plastic andis also referred to as molding. Molding 500 completely envelopes plate504 and die 506 and is applied between gold ball 508 and gold ball 510,as well as between gold ball 510 and plate 504. In some embodiments,part of plate 504 is exposed to the air for better thermal conduction.

With molding 500 completely enveloping plate 504, die 506 and gold balls508 and 510, removable substrate 502 is removed. Removable substrate 502is used during the packaging process but is not part of the packaged ICdevice. In this example, the removable substrate is peeled away toremove it.

FIG. 6A illustrates a cross sectional view of an embodiment with theremovable substrate removed. In this example, only molding 600 andraised leads 602, 604 and 608 are extend to the exterior of the package.Plate 610 and die 606 are completely enveloped by molding 600, as aregold balls 620 and 622 and pads 616 and 618. In this example, the raisedleads are connected to a gate, source and drain of a MOSFET die. Raisedlead 602 is connected to a gate since in this example pad 616 is locatedat a gate. A source is located at pad 618, so raised lead 604 isconnected to a source. Plate 610 provides an electrical connection fromthe drain (located at unprocessed surface 612) to raised lead 608.Raised leads 602, 604 and 608 provide exposed electrical connections forthe PCB to attach to.

FIG. 6B illustrates a bottom view from view VI of an embodiment with theremovable substrate removed. In this example, there are three types ofraised leads exposed to the exterior of the device. Raised lead 602 iselectrically connected to a pad which in turn is connected to a gate.Raised leads 604 are electrically connected to pads which in turn areconnected to a source. Raised lead 608 is electrically connected to aplate which in turn is connected to a drain.

In some embodiments, the processes described are performed on multipleparts simultaneously. For example, multiple dies may be mounted on thelead frames supported by a large removable substrate. After molding, theentire piece is die sawed into individual devices and the substrate isremoved from each device. Alternatively, the substrate may be removedbefore die sawing. In another embodiment, multiple dies are processed onthe same silicon wafer and the whole wafer is mounted on the removablesubstrate. The layout of lead frames on the removable substrate matchesthe layout of dies on the wafer. The wafer-substrate combo is diced intonarrow bars or individual devices to attach the top plate. The substrateis removed after molding. In some embodiments, the cutting process isperformed at a different step.

In some embodiments, there are variations to the semiconductor packagingprocess described above. For example, one variation is to connect acomponent to multiple components. Another variation is to removecomponents from the semiconductor packaging process described above. Insome embodiments, geometries of components are different from thatdescribed above.

FIG. 7A illustrates a cross sectional view where one raised leadreplaces multiple raised leads for the source. In this example, raisedlead 702 is connected to gold ball 710 and other gold balls not shown.Gold ball 710 is connected to pad 712. Raised lead 700 is electricallyconnected to a gate through gold ball 708 and pad 706. Using adhesive716, raised lead 704 is electrically connected to a drain through plate714. Raised lead 702 is electrically connected to pad 712 and thereforeto a source. Mounting surface 720 is the surface of the packaged ICdevice which is in contact with a PCB when the packaged IC device ismounted. Opposite mounting surface 720 is the top surface 718.

FIG. 7B illustrates a bottom view from view VII of an embodiment whereone raised lead replaces multiple raised leads for the source. In thisexample, there are three raised leads and raised lead 702 is connectedto multiple gold balls (not shown). Raised lead 700 is electricallyconnected to the gate, raised lead 702 is electrically connected to thesource through multiple gold balls and raised lead 704 is electricallyconnected to the drain. In this example, an electrical connection whichdid not exist with the unpackaged die is created using raised lead 702.Mounting surface 720, at which raised leads 700, 702 and 704 areexposed, is in contact with the PCB when the package is mounted. Thisprovides a larger heat dissipation area to the PCB.

FIG. 8A illustrates a cross sectional view of an embodiment where theplate extends to the exterior of the molding. In this example, plate 800is exposed and extends from the interior of molding 802 to the exterior,as do raised leads 804 and 806. Raised lead 804 is electricallyconnected to a gate through gold ball 808 and pad 812. Raised lead 806is electrically connected to a source through gold ball 810 and pad 814.Adhesive 816 connects plate 800 to unprocessed surface 818 and providesan electrical connection from plate 800 to a drain. From the exterior,only molding 802, plate 800 and raised leads 804 and 806 are exposed.

FIG. 8B illustrates a bottom view from view VIII of an embodiment wherethe plate extends to the exterior of the molding. In this example, plate800 is exposed and extends to the exterior of molding 802. Plate 800 iselectrically connected to a drain, raised lead 804 to a gate and raisedlead 806 to a source. The plate 800 and raised leads 804 and 806 aresurrounded, but not completely, by molding 802. When mounted on a PCB,raised leads 804 and 806 and plate 800 are in contact with the PCB.

FIG. 9A illustrates a side view of an embodiment where the raised leadsextend to more than one exterior surface of the molding. In thisexample, raised leads 902, 904 and 906 extend to the exterior of molding900 at more than one surface. One of the surfaces at which this occurs,the side surface, is illustrated in this figure. Raised lead 902 iselectrically connected to a gate, raised lead 904 is electricallyconnected to a source and raised lead 906 is electrically connected to adrain.

FIG. 9B illustrates a bottom view from view IX of an embodiment wherethe raised leads extend to more than one exterior surface of themolding. In this example, raised leads 902, 904 and 906 extend to theexterior of molding 900 at more than one surface. One of the surfaces atwhich this occurs, the bottom surface, is illustrated in this figure.Raised lead 902 is electrically connected to a gate, raised lead 904 iselectrically connected to a source and raised lead 906 is electricallyconnected to a drain. When mounted on a PCB, raised leads 902, 904 and906 are in contact with the PCB. The side exposure provides bettercontact to the PCB.

FIG. 10A illustrates a top view of an embodiment where the shape of theplate is different from that illustrated above. In this example, oneplane of plate 1000 is not in the shape of a quadrangle. Rather, plate1000 is in the shape of an “E” where three fingers extend from a commonbase. Plate 1000 is connected to die 1002. In order to illustrate theshape of plate 1000, there is no molding shown in this figure. In thisexample, the shape of plate 1000 is used to reduce thermal stress. Asmaterials of the semiconductor package thermally expand at differentrates with temperature, a device with a plate in the shape of plate 1000is less stressed than a device with a plate in the shape of a rectangle.In this example, plate 1000 is shaped such that there are two planeswhich are parallel to each other. Only one plane is illustrated in thisfigure.

FIG. 10B illustrates a cross sectional view from view X of an embodimentwhere the shape of the plate is different from that illustrated above.In this example, plate 1000 is connected to die 1002 by adhesive 1014.In order to illustrate the shape of plate 1000 and be consistent withthe previous figure, there is no molding shown in this figure. In thisexample, plate 1000 is shaped such that there are two planes which areparallel to each other. Only one plane is illustrated in this figure.

Although the foregoing embodiments have been described in some detailfor purposes of clarity of understanding, the invention is not limitedto the details provided. There are many alternative ways of implementingthe invention. The disclosed embodiments are illustrative and notrestrictive.

1. A semiconductor package having a top surface and a mounting surfaceincluding: a die having processed surface facing towards the mountingsurface having exposed metal connections at the processed surface; aconducting connecting material disposed on the exposed metalconnections; a first deposit of a plating material contacting theconducting connecting material; a plate comprising substantially ofthree planar portions, wherein: the first portion of the plate isattached to the unprocessed surface of the die; the second portion ofthe plate is connected substantially perpendicularly to the firstportion of the plate; the third portion of the plate is connectedsubstantially perpendicularly to the second portion of the plate and isparallel to the plate of the first portion of the plate; and the thirdportion of the plate is attached to a second deposit of the platingmaterial such that the second deposit of the plating material is in thesame plane as the first deposit of the plating material and the thirdportion of the plate is parallel to but not in the same plane as thefirst deposit of the plating material; and an insulating material,having an exterior, formed around the conducting connecting material,wherein: the plating material extends to the exterior of the insulatingmaterial so that the plating material is exposed at least at themounting surface of the semiconductor package; and the plating materialincludes a top portion, a side portion, and a bottom portion and atleast two of the top portion, the side portion, and the bottom portionare at least partially enveloped by the insulating material.
 2. Asemiconductor package as recited in claim 1 wherein the exposed metalconnections are of a thickness that is commensurate with the thicknessof other layers formed during processing of the processed surface.
 3. Asemiconductor package as recited in claim 1 wherein the plating materialis gold.
 4. A semiconductor package as recited in claim 1 wherein theplating material is a noble metal.
 5. A semiconductor package as recitedin claim 1 wherein the conducting connecting material is a gold ball. 6.A semiconductor package as recited in claim 1 further including aconnector attached the die, wherein the die has an unprocessed surfaceand the connector is attached to the unprocessed surface of the die. 7.A semiconductor package as recited in claim 1 further including aconnector attached the die, wherein the die has an unprocessed surfaceand the connector is attached to the unprocessed surface of the die andthe connector is a tape type interconnect.
 8. A semiconductor package asrecited in claim 1 further including a connector attached the die,wherein the die has an unprocessed surface located at or near the drainand the connector is attached to the unprocessed surface of the die. 9.A semiconductor package as recited in claim 1 further including anelectrical connection from a surface of the die other than the processedsurface to the exterior of the insulating material, wherein theelectrical connection extends to a same surface as the plating material.10. A semiconductor package as recited in claim 1 wherein the insulatingmaterial and the plating material are formed using a removablesubstrate.
 11. A semiconductor package as recited in claim 1 wherein theinsulating material and the plating material are formed using aremovable substrate that supports multiple devices which aremanufactured simultaneously.
 12. A semiconductor package as recited inclaim 1 wherein the plating material is configured to be connected to aprinted circuit board.
 13. A semiconductor package as recited in claim 1further including a connector attached the die, wherein the die has anunprocessed surface and the connector is attached to the unprocessedsurface of the die and the connector is configured to be connected to aprinted circuit board.
 14. A semiconductor package as recited in claim 1wherein the insulating material has sides and the plating materialextends to the exterior of the insulating material such that the platingmaterial is exposed on a plurality of the sides of the insulatingmaterial.